Easy!Appointments has server-side request forgery in CalDAV connection test that exposes the deployment's internal network

Easy!Appointments is a self hosted appointment scheduler. In versions prior to 1.6.0, Caldav::connect_to_server at application/controllers/Caldav.php:60 hands the request's caldav_url to a Guzzle REPORT call without scheme or host validation. A logged-in backend user (admin, provider, or secretary) reaches loopback, RFC1918, and link-local hosts on the deployment's network. The Guzzle exception path returns the upstream status code plus ~120 bytes of response body in the JSON message field (Caldav.php:74-78), so the SSRF is semi-blind. Version 1.6.0 contains a patch.